It is just a drawing made with ink, most of the times with Chinese or Indian ink. It is made with steel, copper or brass nib. These type of nibs are also used for calligraphy. Many cartoon artists use nibs in order to make their cartoons or comic strips.

As a good example of these type of drawing you can see pictures by Gustave Dore, Jan Marcin Szancer or cartoon artist Will Eisner (who actually used both nib and pencil, ie very fine brush).